 /*******************************************************************************
  * Copyright (c) 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  ******************************************************************************/

 package org.eclipse.core.databinding.observable.value;

 import org.eclipse.core.databinding.observable.IObservable;
 import org.eclipse.core.databinding.observable.Realm;

 /**
  * A value whose changes can be tracked by value change listeners.
  *
  * <p>
  * This interface is not intended to be implemented by clients. Clients should
  * instead subclass one of the classes that implement this interface. Note that
  * direct implementers of this interface outside of the framework will be broken
  * in future releases when methods are added to this interface.
  * </p>
  *
  * @since 1.0
  *
  */
 public interface IObservableValue extends IObservable {

     /**
      * The value type of this observable value, or <code>null</code> if this
      * observable value is untyped.
      *
      * @return the value type, or <code>null</null>
      */
     public Object getValueType();

     /**
      * Returns the value. Must be invoked in the {@link Realm} of the observable.
      *
      * @return the current value
      * @TrackedGetter
      */
     public Object getValue();

     /**
      * Sets the value. Must be invoked in the {@link Realm} of the observable.
      *
      * @param value
      * the value to set
      * @throws UnsupportedOperationException
      * if this observable value cannot be set.
      */
     public void setValue(Object value);

     /**
      *
      * @param listener
      */
     public void addValueChangeListener(IValueChangeListener listener);

     /**
      * @param listener
      */
     public void removeValueChangeListener(IValueChangeListener listener);
 }

